1. Field of the Invention
The present invention relates to a chroma key composition technique.
2. Description of the Related Art
Chroma key composition is a technique for compositing images by overwriting an image from which a region except for a region having a specific color is extracted on another image.
In order to accurately attain the chroma key composition, a region having a specific color needs to be accurately detected. Especially, the contour of the region having the specific color needs to be accurately detected so as to obtain a pleasing appearance of a composite image.
As a conventional technique for accurately detecting the contour for the purpose of chroma key composition, a method of calculating a rough position of a region having a specific color based on color information, and calculating its outline from luminance information has been proposed, as disclosed in patent reference 1.
[Patent Reference 1] Japanese Patent Laid-Open No. 4-35279
However, the conventional chroma key composition is done under the assumption that an image including a region having a specific color is free from noise, and it is difficult to apply if an image is noisy.
For example, noise is generated in an image when an image is transferred via a wireless communication. Upon transferring an image via a wireless communication, if that image picks up atmosphere noise during transfer, the image suffers any loss of information (noise).
In addition, if an image has significant noise, the color of the image is different from an original color, and detection of a region having a specific color often fails upon the chroma key composition. For this reason, the chroma key composition cannot be normally done for noisy images.